basically,
ASA SC is sibeh ho!
2.2L gives you 100bhp extra,
330i goes up to 330bhp,
M3 capable of 540bhp.
This is with 0.45 of boost. With 0.9bar, the fella's own Z3 3.0 power increases to 420bhp, with some work on piggyback ECU, headers, and decat.
ASA comes with the blower, the TM12, an intercooler, and a cheating box to override the MAF signals. Americans have fitted on their E46 for a couple of years, and forum feedbacks have been mostly positive for reliability.
ASA is good.
Everyone should install one.
Now.